The use of an infrared camera for preventive detection of a feverish person at the entrance of your establishments.

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1. How to prevent the spread of a virus in a work environment?

The answer is none other then the sanitary hygiene, social distancing and limiting the access to your institution. As a professional thermographer, I am often asked if the use of an infrared camera, at entrances and exits to establishments, helps limit the spread of a virus like Covid-19. The answer is yes.

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It helps to quickly sort the people who may be subject for a thorough examination. By following the strict procedures that complies with ISO standards, developed since the SARS event, it’s effectiveness is undoubtful but not infallible. The camera does not permit us to conclude that a person is suffering from an infectious disease. Only a certified health professional can issue such a diagnosis.

To have a higher rate of success, several factors must be considered: using the right choice of camera and the steps in place for reading measurement are two important factors that should not be overlooked. However, if the infected person shows no symptoms of fever upon arrival, it will be harder to prevent contamination.

1.1 The choice of the appropriate thermal camera.

To obtain the temperature reading closest to that of the internal body, without it being too affected by the surrounding temperature, it is necessary to obtain the temperature at the lacrimal caruncles of the eye. It is this tiny surface that is found in the inner corner of the eye.

Laurentide 1june20 3Source: Clinique de l'oeil

To successfully obtain an effective temperature reading on such a small area, you need to make sure that you can focus an amount of 4x4 pixels in this region. If you’re using a mid-resolution camera on the market, 320 x 240 pixels, you’ll need to make sure that the face is well framed on the screen so that it completely covers the screen, from bottom to top. Using a camera with a better resolution is therefore useful if we want to frame our subjects in a more natural way, such as a photo of a passport or driver's license. The sensitivity of your device is also important. We strongly suggest to have the sensitivity lower than 50mK to increase the accuracy of the device, in comparison with a black body and the detection mode.

Laurentide 1june20 4Picture taken with the FLIR T620 camera to the subject 1.5m
IR resolution 640 x 480 pixels
Lens 25mm FOL
Sensitivity <40 mK @ 30 ° C

1.2 What are the best practices? 

The different thermal camera models overflow market. More and more companies have them, but the performance of these vary widely. There is certainly a reason why we find cameras at $500 and others at around $70K. Their limits are decreasing in relation to their value, but a limit which connects almost all is their level of precision of ± 2 ° C (± 3.6 ° F). Therefore, it is important to validate this temperature with reference to a black body. It emits almost perfectly thermal radiation. You can also use the screening mode by implementing ten temperatures that will establish our baseline average. From this average, an alarm is activated when the maximum temperature exceeds the selected deviation. In this way, we rely more on sensitivity then the accuracy of the device.

In addition, this sensitivity has its limits and it must be controlled. By regularizing the screening method with an established distance between the subject and the camera, and taking into account the resolution of our camera versus the lens, we can establish the minimum reading surface, the MFOV. This must be less than the targeted area of the inner point of the eye. If our MFOV is higher than our target, its temperature reading will include other surfaces which will distort our reading. Surfaces such as the nose, eyelashes, cheeks, are easily influenced by the surrounding temperatures. It is also good practice to use the temperature zone by activating the marker. This ensures that the temperature value comes indeed from the targeted location. You can restrict this area, if the marker points to another target. Finally, the environmental monitoring is also necessary. A tempered room with few or no windows that could let the sunshine directly on the subject is suggested. Make sure the person takes off his glasses too. Having a secondary screen that faces the people so that they can fit themselves. These are all good practices that allow you to effectively identify individuals who should undergo further medical examination. Every detail omitted will only deteriorated your success rate.

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1.3 Should I invest in thermography to strengthen my spread barrier?

This is definitely an essential aid, especially if you have lots of people to allow passage quickly. With proper installation and a well-established procedure, the person's passing can be done in seconds and effectively. Infection control in a work environment is worth it’s weight in gold. The investment pays for itself very quickly. Do not skip on the quality of products in place and make sure that things are done right. And so, you will help control some of the spread.


References

https://www.imcontrol.com.au/news/novel-coronavirus-covid-19/

IEC 80601-2-59: 2017

Medical electrical equipment - Part 2-59: Particular requirements for basic safety and essential performance of screening thermographs for screening for human febrile temperature.

ISO / TR 13154: 2017

Medical electrical equipment - Deployment, implementation and operational guidelines for identifying febrile humans using a screening thermograph.


The Author

Mathieu Touzin, thermograph level 3

Industrial Reliability Solutions, Laurentide Controls, Kirkland, Qc, Canada


About Laurentide Controls

Operating since 1968, Laurentide Controls has been helping industry thrive for over 50 years. We are the largest supplier of automation, and reliability solutions to industries in Eastern Canada.

As an entirely employee owned company, every member of our team is driven by the shared goal of empowering people and advancing industry.

As an Emerson Impact Partner, Laurentide Controls connects customers with world-class solutions, superior local and global technical expertise, and life-cycle services for all of our clients’ automation assets and needs. These capabilities enable us to partner with customers in their journey to be Top Quartile in their industry. www.laurentide.com

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